How to find angle between two inclined plane mirrors?

Two plane mirrors are inclined to each other at an angle. If a ray of light incident on the first mirror is parallel to second mirror, is reflected from the second mirror parallel to the first mirror then what is the angle between the two mirrors.
plz help me solve it.

Staff: Mentor

Two plane mirrors are inclined to each other at an angle. If a ray of light incident on the first mirror is parallel to second mirror, is reflected from the second mirror parallel to the first mirror then what is the angle between the two mirrors.
plz help me solve it.

Use the formula:- angle of deviation between initial ray and final ray=(360-2#) where # is the angle of inclination between two mirrors. First find out angle of deviation then put the value in the formula.